Refining process



Feb. 8, 1944. N. F. MYERS REFINING PROCESS Filed Feb. 20, 1942 NSTPatented Feb. 8, 1944 REFINING PROCESS Norval F. Myers, Short Hills, N.J., assignor to Standard Oil Development Company, a corporation ofDelaware Application February 20, 1942, Serial No. 431,642

8 Claims.

The present invention relates to improvements in the art of reninghydrocarbon oils, and more particularly it relates to a continuousprocess of treating heavy petroleum oils, such as topped crudes, heavypitches, oxidized asphalts, cracked residua, etc., in order to formmaximum quantities of hydrocarbons boiling substantially within thegasoline range of improved octane ratings and continuously producedsolid coke.

It is, of course, generally known that in modern renery practice, theresidual oil remaining after the crude oil has been distilled atrelatively low pressure as say at about atmospheric pressure, to removenaphtha, gasoline, kerosene, and the like, or, in other words, thatportion of the original crude boiling up to about 800 F., if a greaterquantity of gas oil is required, is subjected to either a viscosityreducing operation or a coking operation. In the first of theseoperations, the oil is heated to about cracking temperatures and then isdischarged into a reaction zone where it is permitted to remain or reactfor a sufficient period oftime to effect a conversion of the charged oilto substantial quantities of gas oil and tar.

In the second type of operation, the conditions are more drastic and theoil is transformed into readily volatizable products (gas oil, gasoline,gas, etc.) and solid coke. In coking oils, the oil heated to 800 to 950F. or thereabouts is discharged into a drum where the reaction proceedsuntil the A drum becomes practically filled with coke whereupon theoperation is discontinued, the oil is removed, the drum is permitted tocool and the coke is removed.

The usual coking practice is to employ two or more coking drums, one ofwhich is in the onstream or coking operation, While the other or othersis or are being decoked. Thendecoking operation is a laborious andtime-consuming one, since in the ordinary refinery practice, the cokingoperation is carried out until a thick layer of coke is deposited on thebottom and theside walls does nothing more than to break up the massesof coke, still leaving considerable coke adherent to the side wall! andbottom of the vessel, and of course this adherent coke must be removedbefore the vessel is put back in the onstream operation.

Another method of coke removal is by means of hydraulic drilling.Hydraulic drilling is however, an expensive process and therefore notgenerally practiced. Thus, we observe that the decoking of a. cokingdrum is a laborious and timeconsuming operation, in the usual practice.

My present invention is primarily directed toward a combined coking andcatalytic cracking operation in which I form a high octane numbergasoline and a hard, friable, relatively oil-free coke which may becontinuously removed from the system thus obviating the necessity ofintermittent shut-downs.

Further, my present invention not only differs from the prior practicein the details enumerated hereinbefore, but it further differs in that Iconduct the coking operation in the presence of a powdered material,fwhich powdered material forms nuclei about which the formed coke may bebuilt up to form granules or lumps.

Another important object of my invention is that I produce a gas oil bycoking which is particularly suitable as a catalytic cracking stockbecause of the fact that the coke-forming constituents are substantiallyremoved during the coking operation.

In general then, the objects of this invention include treating aresidual petroleum oil to: (a) secure maximum quantities of high octanegasoline, (b) desired quantities of gas oil, either for sale as a fuelor for catalytic cracking, and (c) continuously produce high qualitycoke of saleable quantity.

Other and further objects of my invention will appear from the followingmore detailed description and claims. Y

In order to afford a better understanding of my present inventionreference is had to the accompanying drawing which contains a ow diagramindicating diagrammatically the various steps performed -in a preferredmodification of my present invention.

I shall refer to the drawing in detail and shall set forth a specicexample in which I desribe the manner of processing a given feed stock.

A topped or reduced `West Texas crude petroleum oil having an A. P. I.gravity of about 18 is charged to the system .shown in the drawingthrough line I and thereafter pumped by pump 3 into a furnace 4 wherethe residual oil is heated to a temperature of'from about 800 F. to 850F. under a pressure preferably in the range of from 10 lbs. to 20lbs/square inch gauge, but in any event below 100 lbs/square inch gauge,with optional use of steam. During this heating, a maximum quantity ofsuperheated heavy gas oil vapors are produced and the entire product isthen discharged through line 8 into a separator I0. From separator l thebottoms fraction was withdrawn from line I2 carrying pump I4 and thendischarged into coil l in a furnace I6, where the said liquid fraction`was further heated to a temperature of from about 850 F. to 925 F.During this heating. the heavy oil undergoes viscosity reducing toproduce further quantities of gas oil, which gas oil was thensuperheated to the range indicated. The overhead fraction fromseparation drum I0 was withdrawn through line and discharged into coilI4 of furnace I5, as is indicated in the drawing. The superheated vaporsoriginating in line 20 were withdrawn from furnace I5 through line 22and thence discharged into an indector where they were mixed with anon-catalytic powdered material withdrawn from the supply hop` `rthrough a standpipe 32 carrying a slidin valve 35 adapted to control theflow of material in said standplpe. Instead of injection means 25, anyother suitable mixing means may be provided. The solid material mixed in25 with the oil vapors may be powdered carbon in the form of charcoal,or it may consist of wood flour, coal dust, powdered petroleum coke andthe like. Preferably this material has a particle size of from 20-100mesh.

A suspension of the powdered solid material in the oil vapors is formedin mixer 25, and this suspension is then discharged into a reactor 40.The powdered material and oil vapors are mixed in such proportions thatwithin the reactor the concentration of the solid material in the vaporsis from about l5 to 35 lbs./cu. ft., taking into consideration thevapors released from line 42 within the said reactor. The oil in line402 is that formed in the previoigly mentioned viscosity reducingoperation and normally will haveintermixed therewith oil vapors. Thecombined liquid oil and vapors in line 42 are discharged into a pointnear the bottom of reactor in the form of a spray or mist formed by anatomizer 44, spray head or the like. as indicated in the drawing, Withinthe reactor 40, the oil introduced through line 42 undergoes coking andthe coke which is produced forms particles about the solid materialoriginating in hopper 30, the latter serving as a sort of nuclei aboutwhich the formed petroleum coke coats or deposits to form pea size lumpsor larger aggregates. In the coking operation, the material originatingin hopper 30, if it be cellulosic, say sawdust, etc., undergoescarbonization so that with respect to the operations in reactor 40 bothorganic and petroleum coke may be formed. The coke formed in reactor 40may, for the most part, be withdrawn through an outlet pipe in the formof lumps having a particle size of say about 1% inch to V4. inch on theaverage. The discharging coke is preferably sprayed with water from pipe5I to cool it so that it will not ignite upon contact with theatmosphere. This coke, because of the manner in which it is produced, ishard, friabie, substantially ash-free and dry and provides a saleablefuel. It may be necessary periodically to discontinue-the operationtowithdraw coke which has become too massive to be carried up to the levelof draw-ofi' 50 and in that event, the coke may be withdrawn throughmanhole 45, or this massive coke may be withdrawn continuously withoutshutting down the coking drum operation by substituting for manhole 45 agas seal through which the coke may bev withdrawn. These gas seals arewell known and include liquid pumps, etc., through which the cokegravitates and is withdrawn from the bottom while vapor escape isprevented at this point by said seal. It should be pointed out that inorder to assist in the operation carried out in reactor 40 superheatedsteam or heated hydrocarbons from some source, say at temperatures of850 F. or higher may be discharged into the bottom of reactor 40 throughline 55. This superheated steam aids in the vaporization of thevaporizable portions of the oil in reactor 40.

A portion of the vapors in line 22 may be bypassed around the cokingvessel 40 and mixer 25 and discharged directly to the catalytic crackingstep, hereinafter more fully explained.

The vapors formed in reactor 40 are withdrawn overhead through line 50and discharged into cyclone separator 62 where coke particles, if any,entrained in. the vapors are separated and withdrawn through pipe 65.The coke ilnes in line 65 after drying the same with steam or the likemay be recycled to hopper 30 through line 3|. The vapors, on the otherhand, are withdrawn through line B6. `If these vapors still containparticlesvof carbon or c'oke, it is advisable to pass them through oneor more additional separators, such as cyclone separators or electricalprecipitators, to substantially free vapors of solid material. Thevapors in line 56 were discharged into a reaction vessel IIJ after firstmixing therewith in mixer 69, a cracking catalyst, preferably in theform of a powder to form a suspension. The catalyst may be an acidtreated clay such as superfiltrol, bauxite, bentonite, or syntheticgels, alumina and silica or magnesia. The catalyst preferably has aparticle size of 100 or 400 mesh. The amount of catalyst mixed with thevapors inline 55 should-be so proportioned as to provide a suspensionfor Yreactor 10 having a density of about 1-5 lbs./cu.

ft. In reactor 'l0 the vapors undergo cracking to form substantialquantities of gasoline having a high octane number. The operatingconditions prevailing within reactor 10 in order to effect the desiredresult were as follows:

Temperature degrees F-; 850to950 Pressure --.lbs/sq. in..- Oto 10Residence time of vapors in reactor seconds-, 5to 25 After beingsubjected to the foregoing conditions, the reaction products werewithdrawn through line 'l2 and discharged into cyclone separator l5where the catalyst is separated from the reaction products, withdrawnthrough line 80, thence regenerated in regenerator 85 preferably bycombustion with air or other regeneration gas of tarry and cokeyconstituents formed thereon as a result of the operation taking place inreactor 10.

The method of regenerating catalyst of the kind here in question is wellknown to the art and need not be described in detail. It may merely bestated that the catalyst is regenerated by mixing it with air or otherfree-oxygen-coneffect the desired regeneration or reviviflcation.-

The art also is well aware that certain precautions must be observed inorder to prevent injury to the catalyst, these precautions involvingessentially the steps of diluting the regeneration Y gas (if it is airor oxygen) with inert gas to prevent the acquisition of suchtemperatures by the catalyst as will cause baking or fusing, or it mightinvolve carrying out regeneration under super-atmospheric pressure tocause the regeneration gas to promote active combustion of the catalystcontaminants at a substantially lower temperature than may be had atnormalatmospheric pressure. The regenerated catalyst is reintroducedinto line 66 through line 90. Cony servation of energy may be effectedby mixing hot uncooled catalyst recovered from the regeneration zonewith the vapors in line 66, thus providing at least a portion of thesuperheat necessary to eifect the desired conversion in reactor 'l0 andalso to compensate, at least in part, for the heat absorption resultingfrom the endothermic nature of the reaction in vessel l0.

Reaction products are recovered from cyclone separator l5 through line|00 and, as before, these vapors are passed through additionalseparators to free the vapors completely of solid material. The vaporsare then discharged into a fractionating column |02. In the drawing I Khave shown a catalytically cracked gasoline withsystems. The productionof a I coke a viscosity reduced petroleum oil residuum,

and in another stage thereof, I catalytically crackl the readilyvaporizable products formed in the viscosity reducing stage, as well asvirgin gas oil, etc., to form high yields of high quality gasoline. Ashereinbefore enumerated, the maior features of my improvedprocessinclude the following: (1) continuity of operation with respectto the coking phase; (2) an integrate vis-breaking, coking and crackingoperationV all contributing toward the end result, namely, theproduction. of commercially saleable cokel and high quality gasoline;(3) the advantages of heat conservation made possible by anuninterrupted chain of operaticns, including viscosity reducing, coking.and cracking, and the transfer of heat from a catalyst regeneration zonewhich operates under exothermic conditions, to zones where endothermicreaction takes place, such as for instance cracking operations; 4) acompact unitary system which, because it operates continuously,eliminates the necessity for intermediate storage tanks or other vesselscommon in interrupted or non-integrating gas oil by viscosity reducingand coking is particularly suitablev for catalytic cracking because ofits low content of y coke-forming constituents.

drawn overhead through line |05 and a cycle stock withdrawn through line|01 which latter may be returned to the inlet side of pump 3 for furthertreatment.

The cracked gasoline in |05 discharged into equipment (not shown) torene and recover a nished gasoline of proper volatility. etc. 'Ihisproduct may be used as such, or it may be blended with other stocks toform a finished gasoline. It is also pointed out that terial may bewithdrawn from the system through line ||0 or may be withdrawn directlyfrom the fractionator through line ||2. The

cycle stock in line |01 may be recycled to linev 20 and in thismodification of my invention, Ait

' is usually advisable to solvent treat the cycle oil to removepolynuclear aromatics such as naphthalene, its derivatives, etc., sincesuch compounds cause excessive coke formation. I have indicateddiagrammatically a solvent treater |62 in line |49. The process ofsolvent treating is itself well known and involves treating the materialwith a selective solvent for the aromatic compounds to form a raffinatewhich is richer in paramnic constituents and therefore more suitable forfurther cracking than the untreated stock. The raffinate is withdrawnthrough line |63 and discharged into line 20 for further treatment. Thesolvent extract is withdrawn through line |66. Also I may hydrogenatethe material o in line |49 preferably catalytlcally and undersuperatmospheric pressure according to standard methods to render thecycle stock more suitable as a cracking stock.

To recapitulate, my present invention relates to the method of producingfrom residual petroleum oils by a continuous method commerciallysaleable coke fuels with a minimum cost of handling and, at the sametime, to produce maximum quantities of high quality anti-knock gasolinefrom the balance of the charging material not reduced to coke.

In its essence, my new process is `preferably a -multi-stage operation,in the one stage of which highly refractory ma the powdered solid Manymodifications of my invention falling within the spirit thereof will beapparent to those familiar with this particular art. In the firstsource. I may charge into the system a whole crude, or I may limit thecharging stock to a heavy gas oil. Depending of course upon the natureof the charging stock, the operating conditions will vary. In a word,the specific example which I have hereinbefore set tive of my inventionand does not impose any undue restrictions thereon. It is my intentionto claim as my invention, the subject matter expressed in precisedetails which I have set forth hereinbefore and all reasonablemodifications thereof which are included therein by necessaryimplication, except matter excluded by the terms of the appended claims.

What I claim is:

1. A continuous operation for treating a relatively heavy hydrocarbonollto produce a hard, friable coke and a maximum quantity of highanti-knock gasoline w 'ch comprises heating the said oil, separating theand a liquid fraction, superheating, the vapor fraction and separatelyheating the liquid fraction, mixing a powdered non-catalytic solidmaterial with the fvaporized fraction, discharging both fractions into acoking' zone, recovering a sensibly dry coke from said coking zone,simultaneously recovering a vapor fraction from said coking zone, mixingthe vapor fraction with a' cracking catalyst, conducting the mixture toagasoline of high octane rating from the said fractionation.

2. The method set forth in claim 1 in which material used. in the cokingoperation is of organic origin.

3. The method set forth in claim 1 in which` the liquid fractionrecovered from the separation forth is purely illustraoil into a vaporfraction zone is subjected to viscosity reducing conditions v prior tointroduction into the coking zone.

' 4. Themethod of treating 'a crude petroleum oil which comprisesheating the said oil to vapor-` ize constituents boiling up to andincluding the 1 gas oil range, separating the heated oil into a vaporfraction and a liquid fraction, subjecting the liquid fraction toviscosity reducing temperatures, superheating said vapor fraction tocracking temperatures, mixing the said vapor fraction -with a powderednon-catalytic solid material to form a suspension, discharging thelatter suspension into a coking zone, discharging the viscosity reducedoil at coking temperatures into said coking zone in the form ofdroplets, permitting the suspension and the droplets of oil to intermixand undergo conversion in said coking zone, forming and withdrawingcontinuously a lump coke in said coking zone, recovering a vaporfraction containing gas oil from said coking zone as an overhead vaporfraction, suspending a powdered catalyst in last-named vapor fractionand subjecting the suspension thus formed to catalytic crackingtemperatures, to form a quantity of high octane rating gasoline and a.gas oil.

5. The method set forth in claim 4 in which the powdered material mixedwith the rst,

named vapor fraction is a powdered petroleum coke.

6. The method set forth in claim 4 in which the gas oil formed in thecatalytic cracking phase is separated from the gasoline fraction andrecycled to be mixed with crude oil.

7. The method set forth in claim 4 in which the gas oil formed in the.catalytic cracking is separated from the gasoline and recycled to thevapor superheating step.

8. The method set forth in claim 4 in which coke fines are present inthe vapor fraction recovered from the coking zone, which nes areseparated from the said vapors. dried and resuspended in the vaporfraction discharged into said coking zone.

NORVAL F. MYERS.

